The key word is at the end of the article, "eventually". It's true that the rate of expansion is slowing but the population is still growing. It's currently around 7.6 billions, but was a little over 2 billions when I was born.
That tripling in a single lifetime not yet over, despite a major world war and the invention of vehicles that kill 1.3 millions each year, is alarming by any standards.
The question now is, at what level will the slowing of growth rate reach equilibrium. Optimists propose at around 9.5 billion, while those more pessimistic say 12 billions. The first will be ok in the short term but not the second. In the longer term neither is sustainable and nor is our current population, since we are depleting the earths resources many times faster than they can be replaced.
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